Personally, here's how I think the HRG Medic Missile could be balanced:
-No medic darts. All healing done by the Medic Missile HAS to consume ammo
-Backblast deals decreased damage, is not a healing source. Arming distance increased. This would prevent the medic or survivalist from healing themselves with the explosion
-Hemoclobber-like explosion. Rather than having lingering healing gas, i think it'd be better for it for its AoE heal to behave more like a Hemoclobber's alt-fire.
-Rocket impacts deal Ballistic_Shell damage instead of RPG7. This is the most important one, since the RPG deals 600 impact damage to scrakes and 150 to everything else. If the impact damage needs to be more impactful, I think 200 Ballistic_Shell should be the most damage it should do, so as to not be TOO good at killing larges
-Needs to weigh more than the Incision, so as to prevent healthrower usage.